JSFiddle - React, Tailwind, and code Playground

HTML

<button type="submit" id="emoji-button">
  <span id="thumb-emoji"></span>
</button>

CSS

#emoji-button {
  border-radius: 19px;
  width: 38px;
  height: 38px;
  text-align:center;
}

#thumb-emoji:after {
  content: "\01F44C";
  font-size: 20px;
}